Realistic network security testing: How a penetration test reveals vulnerabilities before attackers exploit them

  1. An incorrectly set firewall rule. An open port on the VPN gateway. An outdated service in the internal network. In one of our network penetration tests, precisely this combination was enough to gradually work its way from the public internet to the domain controller.</p

  2. Without any special exploits. Only with the methods that a real attacker would use. Quiet, targeted and inconspicuous. Many companies rely on their security architecture. But without a real endurance test, it remains unclear how resilient it really is.</p

  3. Our network penetration test shows how far an external attacker can actually get and what happens if they are already in the internal network.

What is a network penetration test?

A network penetration test (also known as a network analysis or network security audit) is a targeted security check of your IT infrastructure, either from the outside (external) or from within the internal company network. We simulate real attacks to check how far an attacker could penetrate your network and which systems are at risk.

The aim of a network penetration test is to uncover potential vulnerabilities in your IT infrastructure before a real attacker finds and exploits them.

We focus on typical risks such as

  • Misconfigurations in firewalls or network areas that are too wide open
  • Open ports and insecure protocols that provide an unnecessary attack surface
  • Outdated or unprotected services through which attackers could gain access to your system
  • Unclear access rights or a lack of network segmentation, which make it possible to spread laterally through the network unnoticed

We test your network from two realistic attack scenarios:

External attack:
Here we analyze how an external attacker could, for example, gain access to publicly accessible systems via the Internet, such as VPN access, email servers or external web services.

Attack from the inside:
In this scenario, we simulate what would happen if an attacker is already in the internal network, for example through an infected end device or unprotected access in the guest WLAN. The aim is to understand how far it could spread in the network and which systems would be at risk.

Networks are the backbone of every IT system, but many attacks start right here. An undetected vulnerability in the wrong place is enough for an attacker to gain access to sensitive systems. In many cases, the attack goes unnoticed for months.

A network penetration test shows you how an external or internal attacker would proceed and how far they would actually get. You find out where protective measures are effective and where they fail. You gain clarity before things become critical.

A network penetration test specifically analyzes how secure your internal and external network infrastructure actually is from the perspective of a potential attacker. We systematically check configurations, services and protection mechanisms that often have vulnerabilities in practice.  

Typical external test targets (attack from outside): 

  • Open ports and publicly accessible services (e.g. VPN, mail, web server)
  • Vulnerabilities in firewall and routing rules
  • Old software versions with known exploits
  • Insecure authentication methods for external access points
  • DNS, email server configurations (e.g. SMTP, MX, SPF) 

Example: 
Poorly secured VPN access with weak authentication allows unauthorized access to internal resources 

Typical internal test targets (attack from the LAN): 

  • Misconfiguration of switches, VLANs and network segmentation
  • Undetected services or systems in the network (shadow IT)
  • Overused or unnecessarily enabled services (SMB, RDP, FTP etc.)
  • .)
  • Missing access restrictions to shares, printers, admin tools
  • Lateral movement: How easily can an attacker move around the network?
  • Access to sensitive targets such as domain controllers, backup systems, databases 

Example: 
A compromised notebook in the guest WLAN can move into the production network without restriction and gain access to internal servers 

A network penetration test not only checks whether someone can penetrate - but also what would be possible afterwards. This gives you a realistic picture of your current network security and allows you to take targeted countermeasures.

Our approach is structured, practical and tailored to your environment. We follow established standards (e.g. PTES, NIST SP 800-115) and combine manual tests with supporting tools to uncover specific weaknesses - both internally and externally.

Scoping & preparation 

  • Definition of objectives, scope and test limits
  • Agreement on which systems are to be tested or excluded
  • Determination of sensitive areas, special features and communication channels 

Information gathering (reconnaissance) 

  • Discovery of the attack surface from an internal or external perspective
  • Identification of accessible hosts, services, ports and potential weaknesses
  • Collection of technical information on the environment 

Vulnerability analysis 

  • Combination of manual and tool-based checks
  • Detection of configuration errors, outdated systems and attack opportunities
  • Audit of access controls, network rules and open interfaces 

Exploitation 

  • Simulation of controlled attacks on vulnerabilities found
  • Testing of actual exploitability (e.g. access to servers, extension of rights)
  • Documentation of all steps - without malicious interventions in systems 

Report & debriefing 

  • Executive summary
  • Technical report incl. risk classification (CVSS)
  • Recommendations for immediate measures & sustainable improvements
  • On request: Joint final meeting & post-test to confirm closed gaps